Treatment of carpets and pile fabrics



United States Patent 46,586/64 U.S. Cl. 117139.5 Int. Cl. C08d 13/16; C09d /00 3 Claims ABSTRACT OF THE DISCLOSURE A treatment for imparting soil resistant properties to textile fibers selected from the group consisting of natural and synthetic fibers and their blends which includes applying to the textile fibers an aqueous dispersion of polymer of the methyl and/ or ethyl ester of methacrylic acid in amounts up to about 4.0% of the weight of the fibers. Thereafter the fibers are dried at a temperature up to 100 C.

This invention relates to a process for rendering carpets and pile fabrics resistant to soiling.

By carpets we mean floor coverings which contain a significant proportion of textile fibres in their construction. It is of course well known that carpets are particularly liable to pick up soil during use from the feet of people walking across them. Carpets having a pile composed of synthetic fibres or of regenerated cellulose fibres tend to soil particularly rapidly. Carpets which are resistant to soiling in the sense that they soil to a lesser degree or less rapidly are therefore particularly advantageous. Pile fabrics, and in particular upholstery fabrics, which are composed of synthetic fibres or of regenerated cellulose fibres are similarly prone to rapid soiling in used and such fabrics which are resistant to soiling are likewise advantageous.

We have now found that if a substantial proportion of the fibres contained in a carpet or pile fabric are impregnated or coated with a polymer of a methacrylic ester the tendency of the carpet or pile fabric to soil is significantly diminished.

Thus according to the invention there is provided a process for the treatment of the fibres of carpets or pile fabrics which comprises impregnating or coating a substantial proportion of the said fibres with a polymer of a methacrylic ester.

Carpets which may be treated by the process of the invention may be constructed by any known method. Thus the carpet may be one of the woven types of carpet consisting largely of fibrous material, or it may be atufted carpet in which the pile fibres are embedded in a nontextile backing, for example a rubber backing. In any event, in carrying out the process of the invention, a substantial proportion of the fibres are impregnated or coated with the polymer. It is, of course, desirable that at least the fibres constituting the pile of the carpet should be impregnated or coated with the polymer since it is the pile of the carpet that is most subject to soiling during use. This condition is achieved if, for example, the pile of the carpet is sprayed with an aqueous dispersion of the polymer and the carpet is subsequently dried. In the case of tufted carpets, the polymer may be applied to the pile fibres before they are embedded in the backing.

The fibres of the carpet may be any of those known to be used in the construction of carpets. Thus the fibres may be wool or cellulose, particularly a regenerated cellulose such as viscose. They may also be synthetic fibres such as those composed of polyamides, for example nylon, of polyesters, for example polyethylene terephthalate, of

3,433,666 Patented Mar. 18, 1969 polyolefines, for example polyethylene and polypropylene, or of polymers or copolymers of acrylonitrile. Blends of fibres may also be used. Carpets the pile fibres of which consist wholly or mainly of regenerated cellulose, nylon or a polymer or copolymer of acrylonitrile, impregnated or coated with the polymer according to the invention, have a particular advantage over carpets having a pile composed of similar fibres not treated with the polymer since the latter are particularly prone to soiling during use.

Pile fabrics which may be treated by the process of the invention may be composed of fibres of any of the types mentioned above as being used in the construction of carpets. The advantages conferred by the process are particularly evident in the case of upholstery pile fabrics consisting wholly or substantially of regenerated cellulose, nylon or acrylonitrile polymers or copolymers.

The polymers with which the fibres of the carpets or pile fabrics are impregnated or coated are polymers of a methacrylic ester, in particular the methyl and ethyl esters. Copolymers may also be used in which the methacrylic ester is copolymerised with a minor proportion of another ethylenically unsaturated monomer.

The polymer with which the fibres of the carpet or pile fabric are impregnated or coated is conveniently applied to the fibres from an aqueous dispersion of the polymer. The aqueous dispersion is conveniently applied to the carpet or pile fabric itself, but if desired may be applied to the fibres before they are made up into the carpet or pile fabric, for example it may be applied to the fibres in the form of yarn. The aqueous dispersion may be applied to the fibres by any suitable means, for example by dipping, impregnating or spraying, or by the use of a brush or furnishing roller. For application to a carpet or pile fabric itself, padding or preferably spraying are very suitable. After application of the aqueous dispersion, the treated material is dried at temperatures up to about C. It is not, however, essential to use elevated temperatures for drying, and it is possible to treat a carpet already laid on the floor by spraying it with the aqueous dispersion or by applying the aqueous dispersion by a suitable brush or roller arrangement, and then allowing the carpet to dry at the ordinary atmospheric temperature. Upholstery fabric already fitted to furniture and the like may be treated in a similar manner.

The aqueous dispersion of polymer may be made by methods already known to the art, for example by emulsion polymerisation techniques. If desired the dispersion may be prepared in such a way that the individual particles carry an electric charge. For example, the emulsion polymerisation may be carried out in the presence of cationic or anionic surface active agents so as to obtain positively or negatively charged dispersions respectively.

The amount of polymer applied to the fibres of the carpet or pile fabric may vary within wide limits, but in general it is applied in amounts of up to about 4.0% of the weight of the fibres. The concentration of polymer in the aqueous dispersion from which it is applied may also vary within wide limits. It may be as high as 33%, but much more dilute dispersions may be used if desired.

In some cases the carpets or pile fabrics treated by the process of the invention, having fibres impregnated or coated with the polymer, besides being resistant to soiling, have a reduced tendency to acquire charges of static electricity compared with carpets or pile fabrics in which the fibres are not treated with the polymer. This is particularly the case where the carpets or pile fabrics have a pile composed wholly or mainly of nylon or polyacrylonitrile fibres, such carpets and pile fabrics being particularly prone to develop static electric charges, especially at low atmospheric humidities.

The polymer dispersions applied to the fibres of the carpets may contain small amounts of adjuvants such as dispersing agents, stabilising agents, water repellents or wetting agents. In addition, other agents may be incorporated which confer enhanced antistatic protection on the carpets; as examples of such antistatic agents there may be mentioned the following classes:

(a) polyalkenoxy compounds, e.g. the condensates of ethylene oxide with alcohols, such as cetyl alcohol, or with alkylated phenols, such as octylor nonyl-phenol.

(b) the cationic condensation products of formaldehyde with dicyandiamide or mixtures of urea and dicyandiamide reacted in the presence of amines or ammonium salts such as the products which are described in U.K. patent specifications Nos. 19,783/ 38 (as laid open to public inspection), 576,562 and 651,139;

(c) the water-soluble salts of polysulphonic acids, such as polystyrene polysulphonic acid, and of polycarboxylic acids, such as polyacrylic acid.

Preferred antistatic agents are those of class (c).

It is already known to treat carpets and pile fabrics in order to render them resistant to soiling by applying to them aqueous dispersions of certain inorganic substances such as silicic acid, silica, alumina, aluminium silicates, barium sulphate and clays. These so-called white soils are believed to function by filling up the cracks, voids and interstices in the fibres so that they are unable to fill with particles of dirt. A disadvantage of this method of making carpets and pile fabrics soil resistant, however, is that the shade of the carpet or fabric tends to become dull, chalky and delustred. Moreover, it is usually necessary after applying the white soil and drying to brush the carpet or fabric so as to eliminate streakiness or shade differences. Carpets or pile fabrics treated by the process of our invention, however, in which the fibres are impregnated or coated with the polymer, are substantially unaffected in shade, and where the polymer is applied to the carpet or fabric itself the latter does not need any subsequent brushing.

The invention is illustrated but not limited by the following examples in which the parts and percentages are by weight:

Example 1 A composition containing 5 parts of a 50.0% negatively charged aqueous dispersion of methyl methacrylate polymer stabilised with Turkey red oil, 1 part of a 20.0% aqueous solution of sodium polystyrene polysulphonate and 25 parts of water was sprayed on to the surface of a blue polyamide carpet so as to deposit 1.7% of the solid methyl methacrylate polymer on the fibre. The carpet was then dried at room temperature. It possessed a lower surface resistivity than the untreated carpet as is shown by the following measurements, which were carried out at 60% relative humidity and 20 C.:

Megohms Untreated 9 X 10 Treated 7.6 X 10 The treated and untreated carpets were laid in an office corridor for 5 days during which more than 5,000 individuals walked across the carpets. During this period the untreated carpet soiled much more rapidly and to a greater extent than the treated carpet. Apart from visual examination, soiling was also assessed using the Grey scale (1.8.0. Recommendation R105, Part H, and British Standard 2662, 1961).

The assessment was as follows:

Treated against untreated: 34 brighter.

Example 2 A positively charged aqueous dispersion of a methyl methacrylate polymer containing 32.4 parts of the polymer, 1.6 parts of cetyl trimethylammonium bromide and 66 parts of water was sprayed on to the surface of a carpet composed of nylon pile fibres dyed to a deep red shade so as to deposit 1.7% of the solid polymer on to the fibre. After drying the carpet at 60 C. the hue was unchanged and the surface resistivity was reduced as shown by the following measurements:

Megohms Untreated 4.3 X 10 Treated 7.0 10

(The resistance measurements were carried out at 60% relative humidity and 20 C.).

The treated carpet soiled much less readily than the untreated carpet when laid in an office corridor and subjected to floor soiling in the manner described in Example 1. After completion of the soiling trial, the treated carpet was rated 4, brighter against the untreated carpet when assessed using the Grey scale.

Example 3 The dispersion used in Example 2 was applied, in the same proportions, to a nylon carpet dyed to a medium yellow shade. During the floor trial, which was carried out in the same way as Example 1, the untreated carpet soiled much more rapidly than the treated.

Using the Grey sale to assess the soiling, the rating of the treated carpet against the untreated was 2, brighter. Comparative resistance measurements carried out on the carpets before and after treatment gave the following result:

Megohms Untreated -1 2.3 10 Treated 3.9 10

(measured at 60% relative humidity and 20 C.).

Example 4 The dispersion used in Example 2 was applied in the same proportions to an undyed carpet composed of regenerated cellulose fibres (viscose rayon). Floor trials were conducted under the conditions outlined in Example 1. As in the previous examples the untreated carpet soiled more rapidly and to a much greater extent than the treated.

On the Grey scale the treated carpet was rated 3, brighter against the untreated.

Example '5 1 part of a 35.0% non-ionic aqueous dispersion of a methyl methacrylate polymer stabilised with the condensate of nonylphenol with 8 moles of ethylene oxide was diluted with 4 parts of water and the diluted dispersion sprayed on to the surface of an undyed carpet composed of viscose rayon fibres so as to deposit 1.6% of the solid polymer on the fibre. The carpet was dried at 50-60 C.

Portions of the treated and untreated carpets were subjected to floor soiling as described in Example 1. The treated carpet soiled less readily than the untreated carpet. After completion of the soiling trial the treated carpet was rated 3-4, brighter on the Grey scale against the untreated carpet.

Example 6 1 part of a 32.0% positively charged aqueous dispersion of methyl methacrylate polymer stabilised with cetyl pyridinium bromide was diluted with 4 parts of water and the diluted dispersion applied by spraying to a wool carpet dyed to a grey shade so as to deposit 1.0% of the solid polymer on the fibre. The shade of the carpet was substantially unchanged by the treatment. On being subjected to floor soiling the untreated carpet soiled more rapidly and to a much greater extent than the treated carpet.

Example 7 A composition containing 10 parts of a 32.0% positively charged aqueous dispersion of methyl methacrylate polymer stabilised with cetyl pyridinium bromide, 1 part of a 50% aqueous solution of the condensation product of dicyandiamide, formaldehyde and ammonium chloride obtained as described in Recipe 1 of UK. specification 651,139 and 45 parts of water was sprayed onto the surface of a carpet composed of polyacrylonitrile fibres dyed to a yellow shade. 1.7% of the solid polymer was deposited on the weight of carpet fibre. After drying the carpet at room temperature its hue was found to be su stantially unchanged. The surface resistivity of the carpet was reduced as indicated by the following measurements which were carried out at 60% relative humidity and 20 C.:

Megohms Untreated 6.0 x10 Treated 3.1 x 10 Example 8 1 part of a 36.5 negatively charged aqueous dispersion of a methyl methacrylate polymer stabilised with sodium cetyl sulphate was diluted with parts of water and the diluted dispersion sprayed on to the surface of a coloured viscose rayon upholstery fabric, so as to deposit 1.6% of the solid polymer on the weight of fabric. A portion of the treated fabric, together with a similar sized piece of untreated fabric, was attached to a cardboard tube, which was placed in a bottle containing floor soil. The bottle was sealed and then rotated for one hour at room temperature. At the end of this period, the tube and attached patterns were removed from the bottle and the loosely adhering soil shaken from the patterns. The untreated pattern was found to be soiled to a greater extent than the treated pattern.

Example 9' A composition containing 5 parts of a 36.5% negatively charged aqueous dispersion of a methyl methacrylate polymer stabilised w-ith sodium cetyl sulphate, 1 part of a 25.0% aqueous solution of sodium polyacrylate, made by hydrolysing polyacrylonitrile with sodium hydroxide to a degree of hydrolysis of 70%, and 40 parts of water was sprayed on to the surface of a carpet composed of polyamide fibres dyed to a yellow shade. 1.7% of the solid methyl methacrylate polymer was deposited on the weight of carpet fibre. After drying the carpet at room temperature its hue was found to be substantially unchanged. It possessed a lower surface resistivity than the untreated carpet, as is shown by the following measurements, which were carried out at relative humidity and 20 C.:

Megohms Untreated 2.45 X 10 Treated 1.17 10 When subjected to soiling on the floor of an ofiice corridor, the treated carpet was found to soil less readily than the untreated carpet. The soiled treated carpet was rated 3-4, brighter against the soiled untreated carpet when assessed using the Grey scale.

We claim:

1. A treatment for imparting soil resistant properties to textile fibers selected from the group consisting of natural and synthetic fibers and their blends comprising applying to said textile fibers an aqueous dispersion of a polymer of an ester of methacrylic acid selected from the group consisting of the methyl and ethyl esters thereof, the said dispersion containing also sodium polyacrylate as an antistatic agent, the amount of said methacrylic ester polymer which is applied to said fibers constituting up to about 4.0% of the weight of the fibers, and thereafter drying the fibers at a temperature up to C.

2. The treatment of claim 1 wherein the methacrylic ester polymer is a polymer of methyl methacrylate.

3. The treatment of claim 1 wherein the fibers having said methacrylic ester polymer and antistatic agent applied thereto are dried at a temperature ranging from ambient temperature to 100 C.

References Cited UNITED STATES PATENTS 2,406,454 8/1946 Charlton et al. 117l39.5 2,734,835 2/1956 Florio et al 117-1395 X 3,090,704 5/ 1963 Collins et a1. 117---138.8 3,236,685 2/1966 Caldwell et a1. 117l38.8 3,321,819 5/1967 Walter et al. 28-72.6

WILLIAM D. MARTIN, Primary Examiner.

M. R. P. PERRONE, Assistant Examiner.

U.S.Cl.X.R. 

